Conventionally, liquid crystal display devices (LCDs) with a touch panel for use in multifunctional mobile terminals such as smartphones have a structure in which the touch panel is bonded via a bonding portion to the liquid crystal panel, that is, the display device main body of the liquid crystal display device.
Such a bonding portion is known to employ a so-called lamination method in which translucent ultraviolet (UV) curable resin, for example, is used to bond together the liquid crystal panel and the touch panel across the whole surfaces thereof. The lamination method is often employed particularly for high-performance devices because no air layer exists between the liquid crystal panel and the touch panel so that the visibility does not decrease due to reflection generated at the interfaces of such an air layer.
Meanwhile, in the liquid crystal panel, an array substrate with an array of thin-film transistors (TFTs) formed thereon and a counter substrate are disposed in a manner opposed to each other and a driver IC is commonly mounted in the vicinity of an end portion of the array substrate extending outward from an end portion of the counter substrate. Accordingly, when the touch panel is bonded to the counter substrate side, which is positioned on the display side of the liquid crystal panel, a gap is formed between the touch panel and the site of the driver IC on the end portion of the array substrate extending from the end portion of the counter substrate. A force applied from the back side of the gap would cause the end portion of the array substrate protruding from the end portion of the counter substrate to undergo a deflection, resulting in a change in the gap between the array substrate and the counter substrate and therefore a yellow unevenness (yellowing unevenness) within the display area.
Hence, in order to fill such a gap, spacer tape is respectively bonded to the periphery of the driver IC on the array substrate and the touch panel to reduce the clearance difference between the array substrate and the touch panel and, into the remaining portion of the gap that cannot be filled with the spacer tape, low-viscosity UV curable resin or silicon, for example, is casted to completely fill the gap.
In the case of filling the remaining portion of the gap with low-viscosity UV curable resin, however, the portion, if it has a large thickness, is thermally stable but insufficient in stiffness, and thus the yellowing unevenness is still likely to occur. Also, in the case of stretching the UV curable resin used to fill the gap within the display area to the periphery of the driver IC, it is not easy to adjust the amount and position of application of the resin. Further, the portion of the gap that cannot be filled with the spacer tape has a three-dimensional extension and it is therefore necessary to adjust the amount of UV curable resin such that the gap is filled while predicting the flow-in of the UV curable resin into the extension, which makes it difficult to control the resin amount.
On the other hand, in the case of filling the remaining portion of the gap with silicon, stiffness can be ensured and thereby yellowing unevenness at room temperature can be reduced but, at an increased temperature, yellowing unevenness due to thermal expansion will occur. In addition, applying and drying silicon takes man-hours longer than using UV curable resin, resulting in poor manufacturability.